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Date:	Fri, 16 Nov 2012 03:39:46 +0100
From:	Kai-Martin Knaak <kmk AT familieknaak DOT de>
To:	geda-user AT delorie DOT com
Subject:	Re: [geda-user] slotting
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"Peter C.J. Clifton" <pcjc2 AT cam DOT ac DOT uk> schrieb am 14. November 2012:

> This probably won't play well with the renumber tools out there,

Specifically, it does not play well with the built-in renumber tool of
gschem. Attributes -> autonumber-text will always make all refdeses
different even if they were deliberately set to the same value. This is
one of my "favourite" gschem warts.=20


> Finally.. if you do use multiple symbols anywher, there is (or was?) a=20
> problem you have to work around, in that when picking up the symbols
> to retrieve attributes from (e.g. for forwarding to PCB layout), it
> was not clear which of the two symbols would be scanned for attributes.
>=20
> To get around this, add the "footprint=3D..." and any other attributes
> you need to be "machine" readable to both halves of the symbol.

This kind of redundancy creates maintenance issues. E.g. consider a
7414, which is a package with six inverters. In the schematic these
would be six times a NOT symbol plus a symbol for the power pins. All of
them have to be edited if the footprint is to be changed from DIP14 to
SO14.=20
I like to make the footprint value visible in the schematics.
The requirement for footprint attributes on each and every symbol adds
to the clutter in the schematic.

=20
> (If this issue hase has been resolved already, someone please let me
> know).

It has been alleviated, but not quite resolved. Current gnetlist warns
if it finds different footprints to an attribute. However:

* which value gnetlist picks, depends on the order the symbols were
  entered in the schematic. I wrote a patch that makes sure, gnetlist
  output never ever depends on the order of symbols. This patch was not
  accepted by the devs. I still think, this dependence on order is a bug.

* import-schematics in pcb does not show the warnings

* a missing footprint attribute is treated like a footprint with value
  "#f". This effectively enforces to set the footprint attribute on
  every symbol. Else, gnetlist output will be swamped with warnings.=20

---<)kaimartin(>---

--=20
Kai-Martin Knaak

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